While breast cancer is still the most commonly diagnosed form of cancer among American women, the number of patients dying from the disease continues to decline. That's the good news; the bad news is that those statistics do not look so good for African-American women.

A new report from the Centers for Disease Control and Prevention suggests that large gaps between black and white women in terms of mortality and stage of diagnosis continue to persist.

Black women still have a disproportionately higher breast cancer death rate - 41% higher than white women. This finding is based on 2005 to 2009 data, showing that even though African-American women have a lower incidence of breast cancer, they are more likely to die of this disease than women in any other racial or ethnic group.

Diagnosis of breast cancer at more aggressive stages is also more common among black women than white women. There were nine more deaths among black women for every 100 breast cancers diagnosed compared to white women.

The report says that mammography may be less frequently used among black women than white women, based on self-reported data. It's also more common for a longer amount of time to pass between mammograms for black women than white women.

Once a woman receives abnormal mammography results, it takes longer for her to get a diagnosis if she's black than if she's white, studies have shown.

The report also points out that black women more commonly have subtypes of tumors that are harder to treat, especially a kind called triple negative breast cancer.

"Further research is needed to determine the etiology of biological characteristics of breast cancer in black women to design effective prevention and treatment strategies," the report said.

This report also points out that African-American women still aren't receiving the same quality of breast cancer treatment as white women typically do. White women are also more likely to begin treatment within 30 days of diagnosis.

If women of both races received the same treatment, death rates could fall by almost 20%, Dr. Marcus Plescia, Director of the Division of Cancer Prevention and Control at CDC, told reporters Wednesday.

The Affordable Care Act is designed to allow access to health care that wasn't possible for some women before, including mammograms, said Ileana Arias, principal deputy director for the CDC.

This report does have some limitations that it acknowledges: The study did not verify cause of death. Race and ethnicity could have been misclassified, and the population estimates from the U.S. Census Bureau may have errors.

Breast cancer is the second leading cause of cancer death in the United States, and leads to about 40,000 deaths annually among all women.

In general, more research is needed to probe the reasons for such racial disparities and develop interventions that benefit all groups. More aggressive breast cancer types also require more research in terms of screening and treating them.